How do you graph f(x) = (x-2)^2 - 1 on a coordinate graph?

1 Answer
Jun 25, 2018

Refer to the explanation.

Explanation:

Graph:

f(x)=(x-2)^2-1 is a quadratic equation in vertex form:

f(x)=a(x-h)^2+k,

where:

a=0, h=2, k=-1

In order to graph a parabola, the vertex, x- and y-intercepts, and additional points need to be determined.

Vertex: maximum or minimum point of a parabola

The vertex is the point (h,k): (2,-1)

Y-intercept: value of y when x=0

Substitute y for f(x) and substitute 0 for x. Solve for y.

y=(0-2)^2-1

y=(-2)^2-1

y=4-1

y=3

The y-intercept is (0,3).

X-intercept: values of x when y=0

Substitute 0 for y and solve for x.

0=(x-2)^2-1

Expand.

0=x^2-4x+4-1

Simplify.

0=x^2-4x+3

Factor.

0=(x-1)(x-3)

Set each binomial equal to 0 and solve for x.

x-1=0

x=1

x-3=0

x=3

x-intercepts (roots): (1,0) and (3,0)

Additional point: choose value of x, plug it into the equation and solve for y.

x=4

Substitute 4 for x and solve for y.

y=(4-2)^2-1

y=2^2-1

y=4-1

y=3

Point: (4,3)

Summary

Vertex: (2,-1)

Y-intercept: (0,3)

X-intercepts: (1,0), (3,0)

Additional point: (4,3)

Plot the points and sketch a parabola through them. Do not connect the dots.

graph{y=(x-2)^2-1 [-10, 10, -5, 5]}